Social media has amply demonstrated its abilities as an outbound tool, a means for government to push information out to its constituents. Municipalities tweet emergency information during crises. Politicians rally friends on Facebook.

Even as these active uses of social media come into their own, newer passive uses are evolving. Rather than shout, government agencies listen: They harvest the chatter, sifting for relevant mentions that might help them to better respond to crises and emergencies.

During the Deepwater Horizon oil spill, Tulane University students used Ushahidi, an open source software platform, to aid in the massive cleanup effort. Participants in the Oil Spill Crisis Map project helped visualize data on maps by harvesting reports generated through email, text messaging, Twitter and other social media platforms.